If expenditure is anything to go by, we are a nation obsessed with skincare. The market intelligence agency Mintel reported that Brits spent £1.18 billion on the stuff in 2019. And during lockdown, 18% of those that have a routine spent longer on it. As we regularly extol the virtues of skincare, this is very pleasing news to us. Since our inception, we’ve gone from evading eczema and treating keratosis pilaris to exploring niacinamide and tackling adult acne (amongst others). Acids – the darlings of the skincare industry – have predictably featured throughout. Although they are undeniably effective, they can also be harsh, which is where lactic acid tends to differ – and why we’re so obsessed with it.
It’s good that you specified skincare here, otherwise we might have launched into a monologue about anaerobic respiration. Chris Caires, Chief Scientist at Perricone MD, tells us that lactic acid can do two things for our skin: exfoliation and acne assasination. The former comes from it being an alpha hydroxy acid. As such, lactic acid “is very effective at exfoliating away the top layer of dead skin by dissolving it.” The acne assasination aspect, however, is because lactic acid is also a short-chain fatty acid. “These short chain fatty acids are powerful prebiotics that can selectively kill harmful acne-causing bacteria on skin while leaving good bacteria alone,” he says.
The large molecule size of lactic acid means “that it doesn’t penetrate deep into the skin cells but works on the surface, making it ideal for more sensitive skin,” says cosmetic scientist and Founder of Oskia, Georgie Cleeve. This is in contrast to glycolic acid, “which is much smaller in molecular size” and therefore does penetrate deep into skin cells. For her, “what makes [lactic acid] so brilliant is that it also hydrates skin.” If you’re more concerned with anti-aging, Lydia Taylor, Elemental Herbology's Education Manager, recommends malic acid: it “will also encourage the production of collagen,” she explains.
For Georgie, “lactic acid is ideal as a gentle exfoliator for all skin types that aren’t looking to correct a particular issue” – a bit like those who use dating apps to “have fun and see what happens.” But that’s not to say “what happens” won’t be something special. Lydia advises that lactic acid can indeed “be used for treatment of fine lines and wrinkles, sun-damaged skin, uneven pigmentation and mild acne.” Either way, McKenzie Bolt, Director of Global Education for Biossance, thinks that lactic acid is wonderful for “those wanting a beginning level AHA product” – which may well be you.
Although “there are some acids that boost sebum production, making them unsuitable for oily skin types,” says Georgie, “lactic is the one acid that is suitable for all.” But “you should just be careful to not overuse it as this can cause irritation,” cautions Lydia.
Products – from night serums and peels to cleansers-cum-masks and moisturisers – containing lactic acid are, of course, as extensive as its uses. If you’re keen for lactic acid to be the main event of your skincare routine, however, most experts agree that it’s best applied – up to three times a week – as an evening exercise. “Daytime is for protection, night time is for repair and regeneration,” Georgie informs us. “Removing dry and dead skin cells removes a layer of protection on your skin, so it’s important to do this when your skin is not requiring protection from UV and pollution.”
We know that "lactic" looks suspiciously like "lactose" but – according to a study published in the American Journal of Physiology – lactic acid was only named as such because the chemist who discovered it in 1780 did so via samples of sour milk – lactic acid itself is completely vegan.